Interval and ratio levels of measurement are continuous. But a host of other variables are not continuous. They’re called discrete or categorical variables, and examples are race (such as black and white), social class (such as high and low), and political affiliation (such as Democrat and Republican). In Chapter 2, we called these types of variables nominal level. You need to use other correlational techniques, such as the phi correlation, in these cases. These topics are for a more advanced course, but you should know they are acceptable and very useful techniques.
